| 摘要 |
PURPOSE:To prevent a float for detecting a water level of a reservoir, etc. from freezing in the winter season, by using a protecting tube made of a surface current heating tube. CONSTITUTION:Steel pipes 1, 1' for constituting a necessary number of surface current heating tubes, whose length is nearly equal to a protecting tube 9 are welded as shown in 20, on the protecting tube 9, and both respective ends are connected by short-circuit pieces 7, 8. 4 and 4' are connecting wires, and as for connection of an electric power source 3, an insulated wire 2 and the steel pipes 1, 1', the insulated wire 2 is a primary circuit and the steel pipes consist of straight line parts of 1, 1' and a bend of 7, against the electric power source 3 in the inductive surface current heating tube, and both its ends are connected by the short-circuit piece 8, therefore, a secondary inducing circuit is formed against the insulated wire 2. By providing such a heat retaining layer 21, necessary electric power for preventing freezing can be reduced to 1/10-odd number. |
